We often cater for veggies and special diets (though not coeliac). One of my tricks is to set up a veggie feast, then cook something like a lovely piece of gammon or beef that the meat eaters can enjoy alongside, and then eaten cold.
At this time of year, a pumpkin or squash, stuffed with rice (extra veges, nuts & raisins etc) looks lovely.
Also, a huge tray of roast vegetables: garlic, onions, peppers, aubergines, tomatoes, slices of fennel with plenty of herbs.
This can be enjoyed hot or cold (I do plenty for left-overs).
Any kind of carbohydrate works with these - they stir in to rice very nicely, as well as being great in sandwiches.
I'd get the following to keep by:
Some plain rice cakes, can be eaten with anything
Oatcakes (ditto)
Mushrooms which can be quickly made into a tasty snack
Eggs (ditto)
A good selection of cheese
And for puddings:
Ice cream (check it's gluten free)
And I'd make or buy a batch of meringues & macaroons.
Standard 'afters' in our house when people are staying awhile is that I put out: ice cream, nice biscuits, fruit, cheese, crackers. Help yourself in whatever order you like.
Hope that helps.